The present invention relates to an optical packet switching system capable of operating at a super high switching speed in the range from several hundred megabits per second to several gigabits per second.
The following documents are available as prior art super high speed packet switching systems:
Document 1. "Application of Self-Routing Switches to LATA Fiber Optic Networks" Chet Day et al. (ISSS '87).
Document 2. "Asynchronous Time-Division Switching: The way to flexible broadband communication networks" P. Gonet et al. (Zurich Seminar '86)
Document 3. "New Directions in Communications" J. S. Turner (Zurich Seminar '86)
Document 4. "A Photonic Knockout Switch for High-Speed Packet Networks" Kai Y. Eng. (GLOBCOM '87)
Documents 1 to 3 disclose systems in which packet switching is hardware-implemented using parallel processors to permit switching of high speed multiplexed packet signals at speeds of 100 to 300 megabits per second which is carried by each circuit served by the system.
However, these switching systems employ electronics technology and therefore have inherently limited switching speeds, switching capacity and power consumption, thus failing to provide compatibility with the increasing transmission speed of optical transmission mediums. Thus, the prior art techniques are almost incapable of meeting the need for serving many circuits with a speed of several gigabits if the electronic technology is pursued in the development of high speed switching.
On the other hand, document 4 proposes the use of photonic technology for implementing packet switching. The use of photonic technology in a circuit switching system has already been proposed. Also proposed is the use of wavelength division multiplexing technology for implementing a compact space division switching network. The use of wavelength division multiplexing technology is also proposed by document 4 as a means for transferring packets from input ports to output ports to implement high speed packet switching.
However, in packet switching systems, buffers are required to store packets contending for the same output port in addition to the transfer function. The buffers employed in the system proposed in document 4 are of electronics type, thus requiring translation between optical and electrical signals. As a result, the amount of energy dissipated by the electronic buffers is substantial and the electronic operating speed of the buffers has an inherent limit which prevents the servicing of many circuits that carry packets of more than 1 gigabit per second.